Pupa. Length 7.5 — 10.0 mm. Antennae of male pupae coiled 2.5 times 

 around body, antennae of female 2 times. Labrum small, with rugose anterior 

 margin; setae short, strong. Intermediate of the 3 setae on anteclypeus 

 light, closer to basal margin than in other species; 3 strong setae on each 

 side near anterior margin; 2 larger setae situated close together some 

 distance from margin more posteriorly on each side. Distal part of 

 mandibles relatively wide, tapering, finely serrated, slightly curved. 



Wing sheaths reaching segments 6 — 7; natatorial setae on mid-tarsus 

 and on first 3 segments of fore tarsus. Posterior-angle processes of 1st 

 abdominal segment distinct, narrow, with nunaerous spinules. Gills absent. 

 Holding apparatus on segments 3— 6, number of spinules: 111:3—4; IV:3— 4; 

 V:3 — 5 + 8 — 17; VI:3 — 7. Dorsal processes of segment 9 with 3 short, brown 

 setae situated close together, and a moderately long seta slightly posteriorly 

 and laterally. 



Anal rods (Figure 752, A) thin, basal part more than twice as long as 

 apical part, curved dorsally beaklike at the end; small dorsal and median 

 spinules between the two parts; setae small, light, 3 along rod near spinules, 4th 

 seta situated near curved apex, very small. Penis sheath and ventral 

 appendages as in Figure 752, B. 



Case 9 — 14 mm long, attached at both ends by an anterior and a posterior 

 disk as well as by thin ligaments all along; posterior membrane with broad 

 elliptical central pore. 



Mode of life and habitats. Lakes, on solid bottom of sand and 

 detritus in open littoral and sublittoral; avoids strong surf; usually at a 

 depth of 1 — 4 m; often in open vegetation on bottom; also on solid bottom 

 in pools and at mouth of rapid rivers. 



Distribution. Northern, west ern, and c entral parts of the European 

 USSR. In addition, Europe. 



2. Mystacides sp., larva nova ■•' 



Full-grown larva. Length, 9.0— 10.2 mm, resembling M . a z u r e a L. in 

 morphology and coloration. Head (Figure 753, A) oblong, flattened laterally 

 in middle, as in M. azurea; main color shining brown; dots distinct, 

 reddish brown. Frontoclypeus with 3 pairs of large dots anteriorly, a 4th 

 pair near curvature of sutures on site of tentorial pits; dots of anterior 

 pair larger than others, slightly closer together but not connected by a dark 

 transverse stripe; the group in posterior part formed by 4 large dots, 3 

 of them in a row, the 4th anteriorly. Dorsal stripes pale anteriorly, 

 indistinct, with 2 large dots at anterior margin and near curvature of suture; 

 4 large dots further along suture, the last at its fork; 2 rows of large dots 

 lateral to coronal suture; rows of dots on site of lateral stripes; a group 

 of 4 large dots ventrally, lateral to gula near occipital foramen. Gula 

 brownish (Figure 753, B). 



Pronotum brownish, lighter anteriorly; white stripe in anterior-angle 

 area relatively wide, distinct, as in M. azurea; dots reddish brown, 

 distinct; middle of sclerite, in contrast to M . a z u r e a , with a narrow smoke 

 brown stripe with small, indistinct dots; a large, dark dot at posterior 

 margin of stripe near median suture; a group of 6 large dots in posterior 



" Described from specimens collected by V. Ch. Dorogostaiskii on 6 November 1908 in Lake Dal'noe, 

 Transbaikalia. 



587 



